Nelson and Tasman Floods

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On Tuesday 13 December, 2011, as people began to plan for summer, it began to rain and didn't stop until Thursday 15 December. The torrential rain was caused by a trough stalled between a low in the Tasman Sea and a high to the east of New Zealand. It was a one in 500 year downpour for Takaka and a one in 250 year event in Nelson.1 A "pipeline" of rain had developed as subtropical moisture barrelled in from the north Tasman Sea.2

The disaster was the worst the region had seen for decades. A third of Takaka's normal annual rainfall (674mm) fell over two days. The coastal strip from Brightwater to north of Hira, including the hills behind Nelson also suffered from the deluge. At Richmond, 280mm was measured over 48 hours - more than a quarter of Richmond's normal annual rainfall.3

Rocks Road slip, Dec. 2011. The Nelson MailClick image to enlarge

A state of emergency was declared on the evening of Wednesday 14 December following a day of heavy rain. The Matai River rose, flooding its banks, precautionary sandbags were laid and several roads were closed.4 Hillsides became waterlogged and slipped - tons of mud, water and debris poured across farmland, roads and into houses.5

By 15 December, the band of intense weather began to move away from Nelson and the region began to assess the damage. There were multiple road closures and damaged properties. Hundreds of people were evacuated from their homes. Residents in Nelson's Wood area were evacuated as police feared a slipping hillside might collapse onto their houses.6 An apartment building on Wakefield Quay was evacuated due to a slip behind the building.7 About 30 homes above a major slip in Rocks Road were evacuated as a precautionary measure.8

State Highway 6 around Nelson's waterfront was closed, with peak traffic gridlocked on the main route between Richmond and Nelson.9 A slip put the city's water supply at risk and contractors worked furiously to stabilise the Maitai pipeline just below the Maitai Dam.10

Cable Bay was cut off for several days with many slips along the only road in to the small community. Network Tasman linesmen were flown in to restore power and supplies were taken in by helicopter.11

Groundwater on the Waimea Plains rose to unprecedented levels and large parts of Rabbit Island remained flooded five weeks later.12

In Golden Bay the year was bookended by floods. In January 2011, floods described as the worst in 169 years, devastated parts of Golden Bay, causing more than $6 million in damage. The swollen Anatoki and Aorere rivers raged through homes, washed stock downstream, destroyed bridges and damaged roads and power lines.13

In the December event, the rainfall was mainly coastal, and the lower country, unaccustomed to such heavy rain, became saturated and bore the brunt of the damage.14People in Ligar Bay fled to higher ground as a wave of trees, mud, rocks and water thundered down the valley.15 Mike Robertson's 430-hectare Wainui Bay dairy farm was ravaged by 12 landslides which covered his paddocks, trapped 300 cows and left the land covered in up to five metres of mud. He expected it would take about a year to clean up the farm.16

Collingwood was cut off by a large slip on Birds Hill, and in Pohara up to 30 Pohara homes were damaged by a dam bursting.17 The winding road between Wainui Bay and Totaranui was blocked by slips and remained closed through the summer.18 In February, the New Zealand Transport Agency agreed to provide $2million for the road's restoration as part of its Golden Bay recovery package.19

It was considered incredible that nobody died in the disaster, but there were a few close calls. Ian Watts (77) was carried several hundred metres from his Clifton property when a deluge of water from nearby Ellis Creek tore through his house and carried him out onto his paddock. He suffered only a broken finger and wound to his hand.20 A huge rock dislodged from the hillside above Rocks Road slammed into the side of a four wheel drive vehicle as the driver waited in a queue of traffic- he was unhurt.21

By Saturday, 17 December, inspections were underway on more than 300 homes throughout Nelson/Tasman and nearly 140 properties were issued with red or yellow stickers.22 In February 2012, about 70 families were still unable to return to their homes. It was estimated that flood repairs and recovery for the whole region would cost around $40 million: about $15 million for Nelson and close to $25 million for Tasman. It was expected that recovery projects would take up to 10 years to complete, with the costs spread across that period.23

Forty five section 124 (red or yellow sticker) notices remained on properties in Nelson - mainly around Haven Road, Tahunanui Drive and Princes Drive by the beginning of March 2012.24

Retired Nelson city engineer, Mac Crampton, said the 2011 flood in Nelson was less severe than a flood in September 1970 when two women died and dozens of Nelson homes were evacuated in what was then described as the worst flooding for almost 40 years.25

There have been a number of major flood events in the Nelson-Tasman region over the years, with severe flooding in 2010, 1986, 1983, 1970, 1957, 1947, 1929, 1904, 1895 - many of these causing severe slips and damage to equal the event of 2011. Search NIWA's historic weather events catalogue for information about floods in the region. Key information sources are also listed as "Further sources" below.

We are collecting your flood stories

The stories will be loaded into the digital archive at Kete Tasman and linked to this story. If you would like to add your Nelson or Tasman experiences, photographs and videos ofthe 2011 flood to this archive contact the Prow or Kete Tasman, or ask for assistance at your local Nelson or Tasman library.

Falconer, B.(1963) Stabilityof the hillside at Tahunanui, Nelson a report to the Nelson City Council, presenting the results of some further investigation into the problem of landslip of the Tahunanui hillside and outlining a scheme to improve the stability of the hillside. Nelson, N.Z.: Nelson City Council.http://www.worldcat.org/oclc/156902795

Poole, A. L. (1983). Catchment control in New Zealand. Wellington, N.Z: Water and Soil Division, Ministry of Works and Development for the National Water and Soil Conservation Organisationhttp://www.worldcat.org/oclc/10309107